Octaves

noun

1. An interval of twelve semitones spanning eight degrees of the diatonic scale, representing a doubling or halving in pitch frequency.

   "The melody jumps up an octave at the beginning, then later drops back down an octave."

2. The pitch an octave higher than a given pitch.

   "The bass starts on a low E, and the tenor comes in on the octave."

3. A coupler on an organ which allows the organist to sound the note an octave above the note of the key pressed (cf sub-octave)
4. A poetic stanza consisting of eight lines; usually used as one part of a sonnet.
5. The eighth defensive position, with the sword hand held at waist height, and the tip of the sword out straight at knee level.